Portable or handheld electronic devices including cellular phones and the like comprise user interface input devices that allow a user to interact with items presented on a display. Examples of user interface input devices include arrow keys, trackballs, trackpads, and more recently, optical navigation modules (ONMs) that detect finger movement. ONMs generally sense a gesture performed upon the module by a user's finger. In conventional ONMs, light is directed to a light transmitting surface upon which an object, such as one or more fingers, are moved. The finger reflects light to a sensor beneath the surface, which transmits information to a processor corresponding to light reflected from the moving finger. The processor interprets the movement of patterns of transmitted data in order to determine the corresponding movement of the finger. In this manner, gestures may be communicated from the user to a processor of the computing device.
However, the performance and effectiveness of conventional ONMs can become hindered as a result of their reliance on specular reflection since environmental factors can affect a conventional ONM's ability to properly detect light reflections.